The present invention is an apparatus for stirring or mixing and a process for adding reagent to a plurality of reaction vessels while simultaneously stirring the plurality of reaction mixtures.
When reagent is added to a reaction mixture, it is generally considered necessary to stir the mixture in order to achieve a homogeneous mixture and to prevent phase separation. Stirring is even more important when the reaction mixture is viscous. If a viscous reaction mixture was not stirred upon the addition of a reagent, it is likely that the reagent would not be distributed homogeneously throughout the reaction mixture which could result in an incomplete reaction and misleading or inconclusive data.
Recently, chemical reactions and materials syntheses have been conducted using combinatorial techniques. In the combinatorial approach, multiple reactions are conducted in parallel. Applying the combinatorial methods to more viscous materials gave rise to a need for parallel stirring or mixing. It became especially desirable to have the capability to stir an array of parallel reaction mixtures while reagent is being added. Others have used agitation-type mixing in parallel; see WO 98/39099. However, the present invention provides the advantages of adding reagent while stirring and adding the reagent to a central portion of the cross-section of the reaction vessel. Additionally, magnetic or shaking stirrers may not be effective enough to homogenize viscous gels. The present invention is designed to simulate the high shear mixers used in large-scale material preparations.
The invention is an apparatus for mixing a reaction mixture in a vessel while at the same time adding reagent to the reaction mixture. The invention is particularly useful when the reaction mixture is viscous as is commonly found in sol gel reactions. The apparatus involves N rotary drive members, where N is at least 2, where each rotary drive member has a hub with material removed from the hub to form a passage through the rotary drive member; a motor drivably associated with at least one rotary drive member; and a stirrer engaged with each of the rotary drive members. A preferred embodiment of the apparatus involves N gears, where N is at least 1, with each gear having a hub and multiple teeth. Material is removed from the hub to form a passage through the hub of the gear. A motor is associated with at least one gear in order to drive the rotation of the gear. N reaction vessels are associated with the N gears; and a stirrer is fastened to each of the gears, with the stirrer extending into the reaction vessel.
The invention also encompasses a method for adding reagent to a plurality of reaction vessels where each reaction vessel contains a reaction mixture. The method begins with providing the apparatus described above. Then reagent is added to the plurality of reaction vessels via conduits that are in fluid communication with the passage through the gear. The multiple reaction mixtures are simultaneously stirred during the addition of reagent by activating the motor and driving the gears.